fix: 测试用例提Bug按钮 + 全局侧边栏阴影统一

1. 测试用例"提 BUG"按钮接入工作台：
   - TestCaseDetailDrawer 传入 onCreateBug callback
   - 点击"提 BUG"关闭测试详情，弹出 BugCreateModal
   - 创建后 Bug 自动关联该测试用例

2. 全局侧边弹窗阴影统一为 shadow-2xl：
   - PlanDetailDrawer: shadow-2xl ✓
   - DevTaskDetailDrawer: shadow-[var(--shadow-lg)] → shadow-2xl
   - TestCaseDetailDrawer: shadow-[var(--shadow-lg)] → shadow-2xl
   - BugDetailDrawer: shadow-[var(--shadow-lg)] → shadow-2xl
   - 所有 Drawer 样式一致，阴影明显

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/components/version/PlanDetailDrawer.tsx

@@ -76,7 +76,7 @@ export function PlanDetailDrawer({ planId, onClose }: Props) {
 
   return (
     <div className="fixed inset-0 z-50 flex justify-end" onClick={onClose}>
-      <div className="w-full max-w-md bg-[var(--bg-card)] border-l border-[var(--line)] shadow-2xl h-full flex flex-col overflow-hidden" onClick={(e) => e.stopPropagation()}>
+      <div className="w-full max-w-md h-full bg-[var(--bg)] border-l border-[var(--line)] shadow-2xl flex flex-col overflow-hidden" onClick={(e) => e.stopPropagation()}>
         {/* Header */}
         <div className="flex items-center justify-between px-5 py-4 border-b border-[var(--line)] shrink-0">
           <div className="flex items-center gap-2">